He is the artistic director of theatre company Mammalian Diving Reflex, has written many plays including A Suicide-Site Guide to the City, White Mice, Who Shot Jacques Lacan?, Radio Rooster Says That's Bad, Over, [boxhead] and pppeeeaaaccceee, and has published one novel entitled Your Secrets Sleep With Me. In addition to the novel he has published four other books with Coach House Books: Inoculations, pppeeeaaaccceee, Social Acupuncture and the most recent [boxhead] (2009). He holds a M.Sc. in Urban Planning from the University of Toronto (2014) and a B.F.A in Acting from the University of Alberta (1988).

Social Acupuncture is both the title of his book and a wing of Mammamlian Diving Reflex where O'Donnell creates work that engages the public and claims to prove the "generosity, abundance and power of the social sphere." The book is an extended essay outlining the possibility for a civically engaged artistic practice as well as an in-depth description and analysis of his work in this field. Social Acupuncture projects include The Talking Creature, Home Tours, Q&ASlow Dance with Teacher, Parkdale Public School vs. Queen Westand Haircuts by Children. With Haircuts by Children O'Donnell worked with a grade 5/6 class at Parkdale Public School in Toronto and Luther Burbank School in Los Angeles, trained them and provided free haircuts to the public by 10-year-olds. During Toronto's 2006 inaugural Nuit Blanche, an all-night art event, he presented Ballroom Dancing, a dance-party DJed by ten-year-olds in a gymnasium filled with thousands of rubber balls. In the 2007 Nuit Blanche he presented Slow Dance with Teacher, an event that offered the opportunity for the public to have a slow dance with university professors and high school teachers. His company, Mammalian Diving Reflex, is the resident art company at Toronto's Parkdale Public School and has created a series of events entitled Parkdale Public School vs. Queen West that brought children together with artists, the public, businesses and cultural institutions along Toronto's rapidly gentrifying Queen Street West. As of March 1, 2013 Mammalian Diving Reflex is the Company in Residence at the Gladstone Hotel, a boutique hotel in Toronto's West Queen West gallery district.

The work of O'Donnell and Mammalian Diving Reflex has been presented in:

His writing has appeared in Pivot, Material, One Hour Empire, GreenTOpia, Public Access, the Canadian Theatre Review, Daily News and Analysis India, Descant, C Magazine, uTOpia and The New Quarterly.

He was the 2000 recipient of the Pauline MacGibbon Award for directors, and has also been nominated for several Dora Awards for his writing, directing, and acting. He has won one of these awards for design. He also received a 2000 Gabriel award for excellence in broadcasting with his CBC piece Crazy Like a Fox. His Mammalian Protocol for Collaborating with Children was awarded the 2012 Canadian Coalition for the Rights of Children Award.